Due to the discovery of tunneling magnetoresistance (TMR), Magnetic Random Access Memories (MRAMs) composed of a magnetic free layer, an insulating barrier layer and a ferromagnetic pin layer have come into play in recent years and are deemed as a promising next generation memory technology. Such MRAMs have their logic levels, e.g., 0 and 1, determined by manipulating magnetic moments of the free layer via electron spinning under applied currents and external magnetic fields, such that the resistance of memory cells can be altered accordingly. Among conventional MRAMs, spin-orbit torque magnetic random access memories (SOT-MRAMs), which adopt the so-called three terminal configuration for signal transmission, have drawn much attention owing to their ability to prevent reliability issues, such as time-dependent dielectric breakdown caused by the writing voltages (current) applied through their insulating barrier layers.
However, the major problem of such conventional SOT-MRAMs resides in that an external magnetic field is required when writing the SOT memory cells thereof. As such, the necessity of having devices to provide the external magnetic field when using the conventional SOT-MRAMs significantly delays the commercialization process of the same.
It is worth noting that skilled artisans tend to reduce the size of memory cells for increasing the areal density of the same. As such, the ferromagnetic material used in the memory cells with reduced size is required to have a sufficient amount of magnetic anisotropy energy for thermal stability. However, one skilled in the art may appreciate that when the size of the ferromagnetic material is reduced to a certain level, superparamagnetism may be incurred due to external thermal fluctuation which adversely affects the thermal stability.